Investigation on mutual traveling influences between the draft tube and upstream components of a Francis turbine unit

Muhirwa, Alexis; Li, Biao; Su, Wen-Tao; Liu, Quanzhong; Binama, Maxime; Wu, Jian; Cai, Weihua

doi:10.1016/j.renene.2020.08.107

Cited by 8 publications

(3 citation statements)

References 33 publications

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“…The study of unsteady phenomena, in particular, the precession of the vortex rope, is carried out both at partial [13] and close to nominal mo des [14] and with increased fl ow rates [15], at which additional cavitation phenomena arise [16]. Experiments have revealed the nonstationary eff ect of the rope precession on the fl ow in the tur bi ne runner [17] and have recorded additional ultra-low pulsation frequencies [18]. Along with expe ri mental studies, numerical experiments have been widely used [19,20].…”

Section: Conclusion the Determined Infl Uence Of Spatial Shape Of The...mentioning

confidence: 99%

Experimental Studies of Pressure Pulsations in Draft Tube Diffuser of Pump-Turbine Models for Heads up to 200 m

RUSANOV,

SUBOTIN,

KHORYEV

et al. 2024

Sci. innov.

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Introduction. Increasing the share of balancing capacities to cover daily peaks in electricity consumption is one of the top priorities of the postwar development of Ukraine’s energy sector.Problem Statement. Today, power plant hydraulic turbines need both to increase effi ciency and to expand their operating range. For example, the new hydraulic units of the Dniester PSP shall operate in turbine mode in the range of 40—100% of rated capacity, while the four previous units operate in the range of 70—100%. This requirement can be met by increasing efficiency and reducing pulsations at low power output.Purpose. Based on studying the infl uence of blade spatial shape of a Francis pump-turbine runners on fl ow parthydrodynamics, to identify the patterns of pressure fluctuations distribution in draft tube diff user of the hydraulic unit model.Materials and Methods. Three options of models (the original and two modifi ed ones) have been studied onthe IMEP ECS-30 hydrodynamic test stand. The runner blades are made of PLA plastic by 3D printing. Pressurepulsations are measured by sensors at two points of draft tube diff user at a distance of 0.2 and 1.5 runner diameters from the runner bottom shroud.Results. Three modifi cations of the pump-turbine runner for heads up to 200 m have been designed and experimentally studied with the use of circumferential lean that diff er from the original version only in relative position of blade profiles. The analysis of obtained energy and pulsation characteristics of the models in turbine modehas shown that the model with the runner having a negative circular blade lean has the best performance. Conclusions. The determined influence of spatial shape of the runner blades on the energy and pulsation characteristics of the Francis pump-turbine model for heads up to 200 m has made it possible to increase its efficiency and to reduce the level of pressure fluctuations in the flow part.

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Section: Conclusion the Determined Infl Uence Of Spatial Shape Of The...mentioning

confidence: 99%

Experimental Studies of Pressure Pulsations in Draft Tube Diffuser of Pump-Turbine Models for Heads up to 200 m

RUSANOV,

SUBOTIN,

KHORYEV

et al. 2024

Sci. innov.

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show abstract

“…In the simulation, the SST k-ω model was chosen to make the solution equations closed. This turbulence model can predict the near-wall flow more accurately [22], and it is widely used in the numerical simulation of Francis turbines [23][24][25]. The flow velocity was determined as the inlet boundary condition, and the pressure (0 Pa) was set as the outlet boundary condition.…”

Section: Simulation Settingsmentioning

confidence: 99%

Investigation on the Effects of Volute Geometric Parameters on the Performance of Pico Francis Turbines Used in Water Pipes

Kang,

Xin,

et al. 2024

Water

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The development of new hydro turbines or the optimization of traditional hydro turbines is one of the research directions that scholars have been interested in to broaden the source of hydropower and improve energy efficiency. In our previous work, a Francis turbine was used in the water supply systems of high-rise buildings to properly control water pressure inside the pipeline and recover excess water energy. In this paper, an optimization study of the volute for the sectional shape, design method, inlet parameters, outlet width, and tongue was conducted using numerical simulations to improve the hydro turbine performance. The simulated results show that a circular section could better enhance the flow velocity inside the volute and make the flow velocity distribution more uniform at the volute outlet, and the equal mean velocity method is a more suitable volute design method in this special condition. The results of range analysis show that the water head reduction increases significantly with the increase in the inlet height, and both inlet height and outlet width have a significant effect on the efficiency. In addition, in the tongue optimization, a larger tilt angle corresponds to smaller output power and water head reduction; a larger stretch length in the limited angle range corresponds to larger output power and lower efficiency. Ultimately, the output power of the hydro turbine was increased by 18.65% and the efficiency by 2.1% through the volute optimization.

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“…Therefore, it is important to accurately capture and analyze the formation of the vortex rope in the draft tube by adopting the appropriate vortex identification methods. [11][12][13][14][15] Attempting to remedy the problems of vorticity-based methods, such methods have been introduced and widely used in vortex structure visualization over the last 30 years. Although second-generation criteria, such as ∆ [16], Q [17], λ 2 [18], and λ ci [19] criteria, have been able to judge the presence of the local rotational motion to some extent, these methods need to adjust the threshold to accurately visualize the iso-surface plot.…”

Section: Introductionmentioning

confidence: 99%

Influence of Upstream Disturbances on the Vortex Structure of Francis Turbine Based on the Criteria of Identification of Various Vortexes

Tao

Wang

2021

Energies

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The inter-blade passage vortex, the vortex rope of the draft tube, and the vortex in the guide apparatus are the characteristics of flow instability of the Francis turbine, which may lead to fatigue failure in serious cases. In the current study, in order to accurately capture the transient turbulent characteristics of flow under different conditions and fully understand the flow field and vortex structure, we conduct a simulation that adopts sliding grid technology and the large-eddy simulation (LES) method based on the wall-adapting local eddy viscosity (WALE) model. Using the pressure iso-surface method, the Q criterion, and the latest third-generation Liutex vortex identification method, this study analyzes and compares the inter-blade passage vortex, the vortex rope of the draft tube, and the outflow and vortex in the guide apparatus, focusing on the capture ability of flow field information by various vortex identification methods and the unique vortex structure under the condition of a small opening. The results indicate that the dependence of Liutex on the threshold is small, and the scale range of the flow direction vortex captured by Liutex is wider, but the ability of the spanwise vortex is relatively weak. The smaller the opening, the more disorderly the vortexes generated in each component and the more unstable the flow field. In the draft tube, the original shape of the vortex rope is destroyed due to the interaction between vortexes. Under the condition of a small opening, an inter-blade passage vortex is generated, affecting the efficient and stable operation of the turbine.

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Investigation on mutual traveling influences between the draft tube and upstream components of a Francis turbine unit

Cited by 8 publications

References 33 publications

Experimental Studies of Pressure Pulsations in Draft Tube Diffuser of Pump-Turbine Models for Heads up to 200 m

Experimental Studies of Pressure Pulsations in Draft Tube Diffuser of Pump-Turbine Models for Heads up to 200 m

Investigation on the Effects of Volute Geometric Parameters on the Performance of Pico Francis Turbines Used in Water Pipes

Influence of Upstream Disturbances on the Vortex Structure of Francis Turbine Based on the Criteria of Identification of Various Vortexes

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